CO18 used to operate as daylight eastbound with RON and would typically leave LGW as CO19 before the second inbound IAH (CO4) would arrive. IAH was usually double-daily 777, but EWR only saw 2x 777 service for brief intervals. 18/19 to LGW more frequently ran with DC-10s and later 767s, as I recall.

I see, thank you for the information. So that's why we don't see four. But usually flights arrive early and say CO4 from IAH was early arriving and CO19 to EWR was running late, there must of been four on the ground at some point, when IAH and EWR were both 2 x 777 daily? Do you know what time CO4 from IAH used to arrive at LGW and CO19 to EWR departed LGW? There must of been quite a bit of spacing between the two flight arrival/departure times?

There may HAVE been four on the deck at once but remember the inbound is often going onto the same gate as the outbound so if I remember was often held remote until the other one cleared.
From 2005 I can see CO35 departing at 0930 with CO4 due at 0955 so no crossover.

I see, thank you. That's a 25 minute slot, there's a lesser chance of a crossover but not out of the question. Is that a big enough window for the departing one to clear without keeping the arriving one holding for too long?

I wondered if anyone had ever photographed 4 at once on the deck atall or any at remote stands? Where any CO 777s ever towed to remote stands to make space for other aircraft?

I know when CO was operating DC10s occasionally the the FCO-EWR or LIN-EWR diverted into LGW if it had a mechanical fault. That would have given maybe 4 x DC10s I don't know if this ever happened with the B777s

I know this is going to be no use to you, but I've definitely seen one but have no idea where. It was most likely in something like Airliner World 10 years ago!

During the early 2000s (I want to say 00-01) it was possible. After 9/11 the second EWR went 764, and then they tinkered with the timings, after that there probably wasn't any time they were there together.

In 2002 and 2003, Continental had 4 daily 777 services: 2 x Houston and 2 x Newark. Even though four where not scheduled to be on the ground at LGW all at once, on many occasions this had to have been the case. I took a look though many archive pages on http://lhr-lgw.co.uk/ and CO4 from Houston had landed for some time before CO35 to Houston had left Gatwick, so there must of been 4 on the ground at this point. Sometimes CO4 arrived early and CO35 left late and the other two inbound from IAH and EWR where already on the ground so there had to be 4 on the ground at once: 4 parked at gates or maybe 2 at the gates and 2 taxiing or 1 taxiing and the other 3 at gates? I'm just thinking someone must have a photograph of four.